Turbulence: cryogenic fluids for high Reynolds number experiments

Enrico Fonda

(Universidad de Nueva York)

Turbulence is referred to as the last great unsolved problem of classical physics. Fundamental questions about the origin, evolution and decay of the turbulent motion are still unanswered.
Recent improvements in modeling and computing power lead scientists and engineers to rely heavily on simulations to solve their problems. However, the board range of scales in turbulence limits the practical use of direct numerical simulations (DNS) to simple problems and to moderately turbulent flows, leaving to experiments a major role in pushing the boundaries of knowledge in this field. Unfortunately, high Reynolds number experiments with fluids like water or air needs to be very large, which makes them hard to manage and very expensive. A solution to this problem is to use low viscosity fluids, such as are cryogenic fluids, as done for example in cryogenic wind tunnels. We review the status and prospects of turbulence experiments using cryogenic fluids, and present turbulent thermal convection as a test case.